diff --git a/Luogu/problem/P7909/P7909.cpp b/Luogu/problem/P7909/P7909.cpp
new file mode 100644
index 00000000..f57bb098
--- /dev/null
+++ b/Luogu/problem/P7909/P7909.cpp
@@ -0,0 +1,11 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, l, r, ans;
+
+int main() {
+    cin >> n >> l >> r;
+    cout << min((int)(ceil(1.0 * l / n) * n + n - 1), r) % n << endl;
+    return 0;
+}